Researchers at the Johns Hopkins Bloomberg School of Public Health found that frequent or unintentional daytime napping among older adults was associated with a higher risk of developing dementia later. The study, published in The Journals of Gerontology: Series A, analyzed long-term data from 995 U.S. Medicare beneficiaries aged 65 and older. Compared with people who rarely or never napped, those who napped most days or every day had a 48% higher risk of dementia. Unintentional napping was associated with a 39% higher risk. The researchers stressed that the observational study cannot prove that napping causes dementia.
A decade of data from nearly 1,000 older adults
The research team used the National Health and Aging Trends Study to follow 995 people aged 65 and older who did not have dementia when the analysis began in 2013. Participants were followed for up to 10 years and reported how often they napped, how long they slept and whether the naps were planned. During follow-up, 417 participants were classified as having possible or probable dementia. The median follow-up period was about five years. Researchers adjusted for age, health conditions, nighttime sleep and other factors before comparing napping patterns with dementia risk.
Frequent and unintentional naps showed the strongest associations
People who napped most days or every day had a 48% higher risk of dementia than those who rarely or never napped. Unintentional napping — falling asleep during the day without planning to — was associated with a 39% higher risk. Naps lasting 30 minutes or less were associated with a 40% higher risk. However, occasional or intentional napping did not show the same clear association after full adjustment. The association for naps longer than 30 minutes also weakened after researchers accounted for nighttime sleep.
Napping may be an early signal rather than a cause
The researchers said the relationship may work in both directions. Changes in brain regions that regulate wakefulness could make a person more likely to fall asleep during the day as dementia develops. Frequent naps could also affect nighttime sleep. The team excluded dementia cases diagnosed during the first five years of follow-up, and some associations remained. That analysis still cannot establish causation. The study relied on self-reported nap habits, and dementia status was determined using a validated classification algorithm rather than a clinical diagnosis for every participant.
The findings do not mean people should stop normal naps
Researchers said larger studies using objective sleep measurements and longer follow-up are needed to determine whether napping itself affects dementia risk. Experts distinguish occasional, planned rest from frequent or uncontrollable daytime sleepiness. If an older adult has recently begun falling asleep unintentionally during the day, possible explanations include inadequate nighttime sleep, sleep apnea, medication effects or other health conditions. The study does not show that stopping naps will prevent dementia; people concerned about a change in sleep patterns should discuss it with a health professional.